JP2008294401A - Composition for organic electroluminescent element, organic electroluminescent element, and method for manufacturing organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having high light emitting efficiency as to an organic electroluminescent element having an organic layer formed by a wet film formation method. <P>SOLUTION: A composition for the organic electroluminescent element is a composition to be used for an organic layer of the organic electroluminescent element and includes an alicyclic ketone compound of which the boiling point is ≥160°C as a solvent component. Further, the composition includes a light emitting material and is preferably a composition for forming a light emitting layer. A method for manufacturing an organic electroluminescent element forms an organic layer such as a light emitting layer by using the composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a composition for an organic electroluminescent device for forming an organic layer of an organic electroluminescent device.
The present invention also relates to a method for producing an organic electroluminescent element using the composition for organic electroluminescent elements, and an organic electroluminescent element produced by this method.

  The organic electroluminescence device usually has an anode, a cathode, and an organic layer such as a light emitting layer and a charge transport layer disposed between the anode and the cathode on a substrate. As a method for forming the organic layer, a vacuum deposition method or a wet film formation method is used.

  The vacuum deposition method has advantages such as being able to form a high-quality film uniformly on the substrate, easy to obtain a device that is easy to stack and has excellent characteristics, and that there are very few impurities from the manufacturing process. Many of the organic electroluminescent devices currently in practical use are based on a vacuum deposition method using a low molecular weight material.

  On the other hand, the wet film formation method does not require a vacuum process and can easily increase the area, and a plurality of materials having various functions can be put in one layer (that is, a coating solution for forming this layer). There are advantages such as being possible.

When the wet film forming method is used, a polymer material is usually used as the material.
However, it is difficult to control the degree of polymerization and molecular weight distribution of polymer materials, deterioration due to terminal residues during continuous driving, high purity of the polymer material itself is difficult, and impurities are included. There is a problem, and there is no practical level other than elements using some polymer materials.

Therefore, as an attempt to solve the above problem, in Patent Document 1 and Patent Document 2, an organic layer is formed by a wet film forming method using a low molecular material or the like. However, these devices have insufficient luminous efficiency and lack practicality.
Japanese Patent No. 3069139 Japanese Patent Laid-Open No. 11-238359

  An object of the present invention is to provide an organic electroluminescent device having an organic layer formed by a wet film forming method and having high luminous efficiency.

In the formation of an organic layer by a wet film-forming method, a layer is formed using a composition in which a layer constituent material is dissolved or dispersed in a solvent. It has been found that there is a significant difference in the luminous efficiency of organic electroluminescent devices.
The present inventors can obtain a low molecular weight material by a wet film-forming method, in particular, by using an alicyclic ketone-based compound having a boiling point of 160 ° C. or higher as a solvent for a composition for forming an organic layer. The present inventors have found that even an organic electroluminescent device having an organic layer can obtain high luminous efficiency, and have reached the present invention.

  That is, the gist of the present invention is a composition used for forming an organic layer of an organic electroluminescent device, characterized in that the solvent component includes an alicyclic ketone-based compound having a boiling point of 160 ° C. or higher. A composition for an organic electroluminescent device.

  Another gist of the present invention is a method for producing an organic electroluminescent device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode on a substrate, wherein at least one of the organic layers The present invention resides in a method for manufacturing an organic electroluminescent element, wherein the layer is formed using the composition for an organic electroluminescent element.

  Still another subject matter of the present invention resides in an organic electroluminescent device manufactured by this manufacturing method.

  ADVANTAGE OF THE INVENTION According to this invention, it is an organic electroluminescent element which has an organic layer formed with the wet film-forming method, Comprising: An organic electroluminescent element with high luminous efficiency can be provided.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. It is not specified in the contents.

[Composition for organic electroluminescence device]
The composition for organic electroluminescent elements of the present invention is a composition used for forming an organic layer of an organic electroluminescent element, and an alicyclic ketone-based compound (hereinafter referred to as a boiling point) having a boiling point of 160 ° C. or higher as a solvent component thereof. , Sometimes referred to as a “ketone solvent”).
In the present invention, the solvent means a liquid that dissolves 0.01% by weight or more of a solute.

  The composition for organic electroluminescent elements of the present invention is usually used as an ink for forming an organic layer of an organic electroluminescent element by a wet film forming method. The organic layer to be formed may be any layer as long as it is an organic layer between the anode and the cathode of the organic electroluminescent element. In that case, each layer can be obtained by preparing the composition for organic electroluminescent elements containing the material and ketone solvent used for each layer, and forming this composition into a film. In particular, the composition for organic electroluminescent elements of the present invention preferably contains a luminescent material and is used as an ink for forming a luminescent layer.

  In the present invention, the wet film-forming method is a method in which a film-forming composition is applied by spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, or an ink jet method to form a film.

{solvent}
<Alicyclic ketone compounds>
The solvent used for the composition for organic electroluminescent elements of the present invention contains an alicyclic ketone-based compound having a boiling point of 160 ° C. or higher.

  In the present invention, the alicyclic ketone-based compound is an alicyclic compound obtained by removing an aromatic compound from carbocyclic compounds having a structure in which carbon atoms are bonded cyclically, A compound in which one or more methylene groups are replaced by a carbonyl group.

In the present invention, since the alicyclic ketone-based compound is used as a solvent for a composition for an organic electroluminescence device for forming an organic layer by a wet film-forming method, the alicyclic ketone-based compound is usually 23 It is liquid at ℃ (room temperature).
The molecular weight of the alicyclic ketone compound is usually 5000 or less, preferably 1000 or less. When the molecular weight exceeds this upper limit, a polymer material may be included, and impurities contained in the polymer material may be mixed.

  The alicyclic ketone compound used in the present invention has a boiling point of usually 160 ° C. or higher, preferably 180 ° C. or higher, and usually 300 ° C. or lower, preferably 260 ° C. or lower. If the boiling point is lower than this lower limit, the volatility of the solvent is increased, and coating unevenness due to a change in the concentration of the composition may occur unfavorably. If the upper limit is exceeded, the drying temperature for removing the solvent increases. In the drying process, the solute material may be deteriorated, which is not preferable. In addition, the boiling point of the solvent in this invention is a boiling point in 1 atmosphere.

  Specific examples of alicyclic ketone compounds suitable for the present invention include cyclopentylcyclopentanone, hexylcyclopentanone, methylcyclohexanone, dimethylcyclohexanone, trimethylcyclohexanone, ethylcyclohexanone, propylcyclohexanone, menthone, acetylcyclohexanone, and cycloheptanone. , 5- to 7-membered alicyclic ketone-based compounds having no carbon-carbon unsaturated bond such as Fencon, 2-cyclohexen-1-one, 3-methyl-2-cyclohexen-1-one, 2- ( 1-cyclohexenyl) cyclohexanone, isophorone, 5,7-membered alicyclic ketone system having a carbon-carbon unsaturated bond such as 2,2,6-trimethyl-2,4-cycloheptadien-1-one Compound etc. are mentioned.

  In the composition for organic electroluminescent elements of the present invention, these ketone solvents may be used alone or in combination of two or more.

  Among these, a particularly preferred ketone solvent is an alicyclic ketone compound having no carbon-carbon unsaturated bond.

  The content of the ketone solvent in the composition for organic electroluminescent elements of the present invention is preferably 60% by weight or more, and more preferably 80% by weight or more. If the content of the ketone solvent in the composition for organic electroluminescent elements is less than this lower limit, the storage stability of the ink may be deteriorated, such as precipitation of a solute.

<Other solvents>
Although the composition for organic electroluminescent elements of this invention may contain other solvents other than the said ketone solvent, Preferably it contains only the above-mentioned ketone solvent as a solvent.

  Solvents that may be contained in addition to the ketone solvent include hydrocarbons such as pentane, hexane, isohexane, heptane, octane, isooctane, decane, dimethylbutane, cyclohexane, methylcyclohexane, ethyl ether, isopropyl ether, diisoamyl ether. , Ethers such as methyl phenyl ether, amyl phenyl ether, ethyl benzyl ether, ketones such as acetone, methyl acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, methyl formate, ethyl formate, isobutyl formate, methyl acetate, isoamyl acetate, methoxyacetate Esters such as butyl, cyclohexyl acetate, methyl butyrate, ethyl butyrate, butyl benzoate, isoamyl benzoate, benzene, toluene, xylene, ethylbenzene, diethyl Aromatic hydrocarbons such as benzene, isopropylbenzene, amylbenzene, diamylbenzene, triamylbenzene, tetraamylbenzene, dodecylbenzene, didodecylbenzene, amyltoluene, tetralin, cyclohexylbenzene, etc. It is not a thing. Moreover, what mixed these 2 or more types may be used.

  When the composition for organic electroluminescent elements of the present invention contains a solvent other than the ketone solvent, the content in the composition for organic electroluminescent elements is 50% by weight or less, preferably 20% by weight or less. Most preferably, as described above, it does not contain a solvent other than the ketone solvent. If the content of the solvent other than the ketone-based solvent is large, the above-described effect by using the specific ketone-based solvent cannot be sufficiently obtained according to the present invention.

{Ingredients}
The composition for an organic electroluminescent element of the present invention contains the above-described alicyclic ketone-based compound as a solvent component, and preferably contains a light-emitting material described later as the composition for forming a light-emitting layer. Contains photo-curing resin and thermosetting resin for the purpose of curing and insolubilizing after film formation in order to prevent these layers from compatibilizing when laminating more than one layer by wet film-forming method You can also let them.
Furthermore, other components such as various additives such as a leveling agent and an antifoaming agent may be included without departing from the gist of the present invention.
As the type of additive, a surfactant is preferable, and examples of the surfactant include a cationic system, an anionic system, and a nonionic system. Among these, a nonionic system is particularly preferable. Examples of nonionic surfactants include silicone surfactants, fluorine surfactants, acetylene surfactants, and the like.

{Solid content concentration}
The solid content (solute) concentration of the material used for each layer such as the light emitting material in the composition for organic electroluminescence device of the present invention is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably. Is not less than 0.1% by weight, more preferably not less than 0.5% by weight, most preferably not less than 1% by weight, usually not more than 80% by weight, preferably not more than 50% by weight, more preferably not more than 40% by weight, Preferably it is 30 weight% or less, Most preferably, it is 20 weight% or less. If the solid content concentration is below this lower limit, it is difficult to form a thick film, and if it exceeds the upper limit, it may be difficult to form a thin film.

{Preparation method}
The composition for organic electroluminescent elements of the present invention is prepared by dissolving a solute composed of a material used for each layer such as a luminescent material in a ketone solvent. In order to shorten the time required for the dissolution step and to keep the solute concentration in the composition uniform, the solute is usually dissolved while stirring the liquid. The dissolution step may be performed at room temperature, but when the dissolution rate is slow, it can be heated and dissolved, or subjected to ultrasonic treatment. After completion of the dissolution step, a filtration step such as filtering may be performed as necessary.

{Moisture content}
When a layer is formed by a wet film forming method using the composition for organic electroluminescent elements of the present invention to produce an organic electroluminescent element, the film formed when water is present in the composition for organic electroluminescent elements used Since moisture is mixed into the film and the uniformity of the film is impaired, the water content in the composition for organic electroluminescent elements of the present invention is preferably as low as possible. In general, since organic electroluminescent devices use many materials such as cathodes that deteriorate significantly due to moisture, when moisture is present in the composition for organic electroluminescent devices, moisture remains in the dried film. However, there is a possibility of deteriorating the characteristics of the element, which is not preferable.
Specifically, the amount of water contained in the composition for organic electroluminescent elements of the present invention is usually 1% by weight or less, preferably 0.1% by weight or less, more preferably 0.01% by weight or less.

  As a method for measuring the moisture concentration in the composition for organic electroluminescent elements, the method described in Japanese Industrial Standard “Method for Measuring Moisture of Chemical Products” (JIS K0068: 2001) is preferable. For example, the Karl Fischer reagent method (JIS K0211). -1348) and the like.

{Uniformity}
The composition for organic electroluminescent elements of the present invention is preferably in a uniform liquid state at room temperature in order to improve stability in a wet film forming method, for example, ejection stability from a nozzle in an ink jet film forming method. . The uniform liquid at normal temperature means that the composition is a liquid composed of a uniform phase and does not contain a particle component having a particle size of 0.1 μm or more in the composition.

{viscosity}
Regarding the viscosity of the composition for organic electroluminescent elements of the present invention, when the viscosity is extremely low, for example, coating surface non-uniformity due to excessive liquid film flow in the coating and drying process, nozzle ejection instability in inkjet film formation, etc. In the case of extremely high viscosity, for example, uneven coating surface due to poor leveling property in the coating and drying process, nozzle non-ejection in ink jet film formation, and the like are likely to occur. Therefore, the viscosity of the composition of the present invention at 23 ° C. is usually 1 mPa · s or more, preferably 3 mPa · s or more, more preferably 5 mPa · s or more, and usually 1000 mPa · s or less, preferably 100 mPa · s or less. More preferably, it is 20 mPa · s or less.

{surface tension}
If the surface tension of the composition for the organic electroluminescent device is too high, the wettability of the composition with respect to the substrate is reduced, and defects such as repellency and poor spread are likely to occur. The surface tension at 23 ° C. of the composition of the present invention is usually 60 mN / m or less, preferably 50 mN / m or less, because unevenness of the coating surface due to defects, poor ejection stability in inkjet film formation, etc. are likely to occur. More preferably, it is 40 mN / m or less, usually 10 mN / m or more, preferably 15 mN / m or less, more preferably 20 mN / m or more.

{Vapor pressure}
When the vapor pressure of the composition for organic electroluminescence devices is too high, problems such as changes in the solute concentration due to evaporation of the solvent are likely to occur, and the discharge stability in inkjet film formation is poor due to the formation of aggregates, that is, flight. Bending or nozzle clogging may occur. For this reason, the vapor pressure at 23 ° C. of the composition of the present invention is usually 50 mmHg or less, preferably 10 mmHg or less, more preferably 1 mmHg or less, and further preferably 0.1 mmHg or less.

{Preservation method}
The composition for an organic electroluminescent element of the present invention is preferably filled in a container capable of preventing the transmission of ultraviolet rays, for example, a brown glass bottle, and sealed and stored. The storage temperature is usually −30 ° C. or higher, preferably 0 ° C. or higher, and usually 35 ° C. or lower, preferably 25 ° C. or lower.

{Composition for organic electroluminescence device for forming light emitting layer}
As described above, the composition for organic electroluminescent elements of the present invention is suitable as a composition for forming a light emitting layer containing a light emitting material.
Hereinafter, the case where the composition for organic electroluminescent elements of this invention is used for light emitting layer formation is demonstrated.
When the composition for organic electroluminescent elements of the present invention contains a light emitting material and is used for forming a light emitting layer, it is preferable to further contain a hole transporting compound or an electron transporting compound. The light emitting material contained in the organic electroluminescence device of the present invention, that is, the light emitting material contained in the light emitting layer of the organic electroluminescence device of the present invention formed using the composition for organic electroluminescence device, hole transport Since the impurity compound and the electron transport compound have few impurities, it is preferably a low molecular compound.

Here, the light emitting material refers to a component that mainly emits light in the organic electroluminescent device, and corresponds to a dopant component in the organic electroluminescent device. That is, the amount of light emitted from the organic electroluminescent device (unit: cd / m ² ) is usually 10 to 100%, preferably 20 to 100%, more preferably 50 to 100%, and most preferably 80 to 100%. If it is identified as light emission from a component material, it is defined as a light emitting material.
The low molecular weight compound is usually a compound having a molecular weight of 5000 or less.

<Light emitting material>
Any known material can be applied as the light emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency.

  For the purpose of improving the solubility in a solvent, it is also important to reduce the symmetry and rigidity of the molecules of the luminescent material, or to introduce a lipophilic substituent such as an alkyl group.

  Examples of fluorescent dyes that emit blue light include perylene, pyrene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof. Examples of the green fluorescent dye include quinacridone derivatives and coumarin derivatives. Examples of yellow fluorescent dyes include rubrene and perimidone derivatives. Examples of red fluorescent dyes include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzothioxanthene derivatives, azabenzothioxanthene, etc. Can be mentioned.

  As the phosphorescent material, for example, a long-period periodic table (hereinafter, unless otherwise specified, the term “periodic table” refers to the long-period periodic table) selected from the seventh to eleventh groups. And an organometallic complex containing a metal.

  Preferred examples of the metal selected from Groups 7 to 11 of the periodic table contained in the phosphorescent organometallic complex include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Preferred examples of these organometallic complexes include compounds represented by the following formula (III) or formula (IV).

ML _(q−j) L ′ _j (III)
(In formula (III), M represents a metal, q represents the valence of the metal, L and L ′ represent a bidentate ligand, and j represents a number of 0, 1 or 2. )

（式（IV）中、Ｍ^７は金属を表し、Ｔは炭素原子または窒素原子を表す。Ｒ^９２〜Ｒ^９５は、それぞれ独立に置換基を表す。但し、Ｔが窒素原子の場合は、Ｒ^９４およびＲ^９５は無い。）

(In the formula (IV), M ⁷ represents a metal, T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is a nitrogen atom, R 7 ⁹⁴ and R ⁹⁵ are not.)

  Hereinafter, the compound represented by the formula (III) will be described first. In formula (III), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.

（上記Ｌの部分構造において、環Ａ１は、置換基を有していてもよい、芳香族炭化水素基または芳香族複素環基を表す。） Moreover, in formula (III), the bidentate ligand L shows the ligand which has the following partial structures.

(In the partial structure of L, ring A1 represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)

  Examples of the aromatic hydrocarbon group include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples include monovalent groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring, etc. Is mentioned.

  Examples of the aromatic heterocyclic group include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring , Sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, monovalent group derived from an azulene ring, and the like.

  In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

  Examples of the nitrogen-containing aromatic heterocyclic group include groups derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples include pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, furopyrrole ring, thienofuran ring, benzoisoxazole ring. , Benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone Examples thereof include a monovalent group derived from a ring.

  Examples of the substituent that each of ring A1 and ring A2 may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; a dialkylamino group; Acyl group; haloalkyl group; cyano group; aromatic hydrocarbon group and the like.

  In the formula (III), the bidentate ligand L ′ represents a ligand having the following partial structure. However, in the following formulae, “Ph” represents a phenyl group.

  Among these, as L ′, the following ligands are preferable from the viewpoint of the stability of the complex.

  More preferable examples of the compound represented by the formula (III) include compounds represented by the following formulas (IIIa), (IIIb), and (IIIc).

（式（IIIａ）中、Ｍ^４は、Ｍと同様の金属を表し、ｗは、上記金属の価数を表し、環Ａ１は、置換基を有していてもよい芳香族炭化水素基を表し、環Ａ２は、置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In formula (IIIa), M ⁴ represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

（式（IIIｂ）中、Ｍ^５は、Ｍと同様の金属を表し、ｗは、上記金属の価数を表し、環Ａ１は、置換基を有していてもよい芳香族炭化水素基または芳香族複素環基を表し、環Ａ２は、置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In formula (IIIb), M ⁵ represents the same metal as M, w represents the valence of the metal, and ring A1 represents an aromatic hydrocarbon group or aromatic group which may have a substituent. Represents a heterocyclic group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.)

（式（IIIｃ）中、Ｍ^６は、Ｍと同様の金属を表し、ｗは、上記金属の価数を表し、ｊは、０、１または２を表し、環Ａ１および環Ａ１′は、それぞれ独立に、置換基を有していてもよい芳香族炭化水素基または芳香族複素環基を表し、環Ａ２および環Ａ２′は、それぞれ独立に、置換基を有していてもよい含窒素芳香族複素環基を表す。）

(In formula (IIIc), M ⁶ represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2, and ring A1 and ring A1 ′ each represent Independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently a nitrogen-containing aromatic optionally having a substituent. Represents a heterocyclic group.)

  In the above formulas (IIIa), (IIIb) and (IIIc), preferred examples of ring A1 and ring A1 ′ include phenyl group, biphenyl group, naphthyl group, anthryl group, thienyl group, furyl group, benzothienyl group, benzofuryl group. Group, pyridyl group, quinolyl group, isoquinolyl group, carbazolyl group and the like.

  In the above formulas (IIIa) to (IIIc), preferred examples of ring A2 and ring A2 ′ include pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, benzimidazole group, quinolyl group, An isoquinolyl group, a quinoxalyl group, a phenanthridyl group, and the like can be given.

  Examples of the substituent that the compounds represented by the formulas (IIIa) to (IIIc) may have include a halogen atom; an alkyl group; an alkenyl group; an alkoxycarbonyl group; an alkoxy group; an aryloxy group; A diarylamino group; a carbazolyl group; an acyl group; a haloalkyl group; a cyano group, and the like.

  These substituents may be connected to each other to form a ring. As a specific example, a substituent of the ring A1 and a substituent of the ring A2 are bonded, or a substituent of the ring A1 ′ and a substituent of the ring A2 ′ are bonded. Two fused rings may be formed. Examples of such a condensed ring include a 7,8-benzoquinoline group.

  Among these, as a substituent for ring A1, ring A1 ′, ring A2 and ring A2 ′, an alkyl group, alkoxy group, aromatic hydrocarbon group, cyano group, halogen atom, haloalkyl group, diarylamino group, carbazolyl are more preferable. Groups.

In addition, preferable examples of M ^{4 to} M ⁶ in the formulas (IIIa) to (IIIc) include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold.

  Specific examples of the organometallic complexes represented by the above formulas (III) and (IIIa) to (IIIc) are shown below, but are not limited to the following compounds.

Among the organometallic complexes represented by the above formula (III), in particular, the ligand L and / or L ′
As the compound, a 2-arylpyridine ligand, that is, a compound having 2-arylpyridine, an arbitrary substituent bonded thereto, and a compound obtained by condensing an arbitrary group thereto is preferable.

  The compounds described in International Patent Publication No. 2005/019373 can also be used as the light emitting material.

Next, the compound represented by formula (IV) will be described.
In formula (IV), M ⁷ represents a metal. Specific examples include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the formula (IV), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, Represents an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group or an aromatic heterocyclic group;

Further, when T is carbon ^{atom, R 94} and ^{R 95} each independently ^represents a substituent represented by the same exemplary compounds and ^{R 92} and ^{R 93.} Also, if T is a nitrogen ^{atom, R 94} and ^{R 95} is not.

R ^{92 to} R ⁹⁵ may further have a substituent. When it has a substituent, there is no restriction | limiting in particular in the kind, Arbitrary groups can be made into a substituent.
Further, any two or more groups of R ^{92 to} R ⁹⁵ may be connected to each other to form a ring.

  Specific examples (T-1, T-10 to T-15) of the organometallic complex represented by the formula (IV) are shown below, but are not limited to the following examples. In the following chemical formulae, Me represents a methyl group, and Et represents an ethyl group.

  In the present invention, the molecular weight of the compound used as the light emitting material is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, preferably 200 or more, more preferably 300 or more. More preferably, the range is 400 or more. If the molecular weight of the luminescent material is lower than the lower limit, the heat resistance is remarkably reduced, gas is generated, the film quality is deteriorated when the film is formed, or the morphology of the organic electroluminescent element due to migration or the like. It is not preferable because it causes change. If the molecular weight of the light emitting material exceeds the above upper limit, it is not preferable because it is difficult to purify the organic compound or it takes time to dissolve the organic compound in a solvent.

  In addition, the light emitting layer may contain any 1 type among various light-emitting materials demonstrated above, and may have 2 or more types together by arbitrary combinations and ratios.

<Hole transporting compound and electron transporting compound>
Examples of the hole transporting compound, in particular, a low molecular weight hole transporting compound include various compounds exemplified as the hole transporting compound of the above-described hole transporting layer, and 4,4′-bis [N An aromatic diamine represented by-(1-naphthyl) -N-phenylamino] biphenyl and containing two or more tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234811) Gazette), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine and other aromatic amine compounds having a starburst structure (Journal of Luminescence, 1997, Vol. 72-74, pp. 985), an aromatic amine compound comprising a tetramer of triphenylamine (Chemical Communications, 1996, pp. 2175), 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′- Spiro compounds such as spirobifluorene (S ynthetic Metals, 1997, Vol.91, pp.209).

  Examples of electron transport compounds, particularly low molecular weight electron transport compounds, include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5-bis ( 6 ′-(2 ′, 2 ″ -bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7-diphenyl- 1,10-phenanthroline (BCP, bathocuproine), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4,4 ′ -Bis (9-carbazole) -biphenyl (CBP) and the like.

  These hole transporting compounds and electron transporting compounds are preferably used as host materials in the light emitting layer.

<Light emitting material / host material ratio>
In the composition for organic electroluminescent elements of the present invention, the weight mixing ratio (light emitting material / host material) of the above light emitting material and the host material of the hole transporting compound or electron transporting compound is usually 0.1 / 99.9 or more, more preferably 0.5 / 99.5 or more, still more preferably 1/99 or more, most preferably 2/98 or more, usually 50/50 or less, more Preferably it is 40/60 or less, More preferably, it is 30/70 or less, Most preferably, it is 20/80 or less. If this ratio falls below the lower limit or exceeds the upper limit, the luminous efficiency may decrease.

[Method of manufacturing organic electroluminescent element]
A method for producing an organic electroluminescent element of the present invention is a method for producing an organic electroluminescent element having an anode, a cathode, and an organic layer disposed between the anode and the cathode on a substrate, Of these, at least one layer is formed using the above-described composition for an organic electroluminescence device of the present invention, and in particular, the organic layer has a first organic layer and a second organic layer adjacent to each other. After the first organic layer is formed by a wet film forming method, the second organic layer is formed on the first organic layer by the wet film forming method using the composition for organic electroluminescent elements of the present invention. A method of forming is preferable.

  In the method for producing an organic electroluminescent element of the present invention, any organic layer formed using the composition for an organic electroluminescent element of the present invention may be any layer as long as it is an organic layer disposed between an anode and a cathode. However, a light emitting layer is particularly preferable.

  The first organic layer and the second organic layer may be any two adjacent organic layers disposed between the anode and the cathode of the organic electroluminescent element, but the first organic layer The hole injection layer and the second organic layer are preferably light emitting layers.

In this case, it is preferable that the composition for organic electroluminescent elements forming the second organic layer does not dissolve the first organic layer. This is because if the materials between the two layers are mixed, the functions of the materials of each layer may not be sufficiently extracted.
In particular, when the first organic layer is a hole injection layer and the second organic layer is a light emitting layer, the hole injection layer does not dissolve in the composition for an organic electroluminescent element of the present invention forming the light emitting layer. Is preferred.

  For example, when the light emitting layer is formed on the hole injection layer using the composition for an organic electric field element of the present invention, the remaining film thickness ratio of the hole injection layer calculated by the following solubility test is 80% or more. Preferably, it is 90% or more, and the remaining film thickness ratio is more preferably 95% or more. In this case, an aromatic solvent or the like is preferably used as a solvent for the composition forming the hole injection layer. Specific examples of the aromatic solvent are described in detail in the description of the hole injection layer below.

  The solubility test is performed by the following steps (1) to (8).

(1) A hole injection layer is formed as a thin film on a glass substrate.
(2) A part of the thin film of (1) is scraped off to form a step between the glass substrate and the thin film (a cross section in the thickness direction of the thin film is exposed).
(3) The step formed in (2) is measured with a stylus type film thickness meter to determine the initial film thickness of the hole injection layer.
(4) A glass substrate with a hole injection layer whose initial film thickness is determined in (3) is placed on a spin coater, and a solvent for organic electroluminescent elements is dropped on the hole injection layer to form droplets. Hold the drop for a minute.
(5) After holding the droplet for 10 minutes, the solvent for organic electroluminescence device of (4) is removed by spinning out.
(6) The glass substrate with a hole injection layer from which the solvent has been removed in (5) is dried at a temperature of 230 ° C. for 12 minutes.
(7) The thickness of the hole injection layer dried in (6) is measured again with a stylus type film thickness meter.
(8) The remaining film thickness ratio is calculated by dividing the film thickness measured in (7) by the initial film thickness and taking the percentage, and the remaining film thickness ratio is estimated as the solubility of the hole injection layer.

  The specific method for forming the hole injection layer and the method for forming the light emitting layer are as described in the section of [Organic electroluminescent device] below.

[Organic electroluminescence device]
The organic electroluminescent device of the present invention is manufactured by the above-described method for manufacturing an organic electroluminescent device of the present invention, and is therefore disposed on a substrate, between an anode and a cathode, and between the anode and the cathode. It has an organic layer, and at least one of the organic layers is a layer formed using the composition for organic electroluminescent elements of the present invention, and in particular, the organic electroluminescent element of the present invention. It is preferable that the layer formed using the composition for light emission is a light emitting layer on the hole injection layer.

  Hereinafter, the organic electroluminescent device of the present invention will be described with reference to the drawings.

  FIG. 1 is an example of a schematic cross-sectional view showing a structural example suitable for the organic electroluminescence device of the present invention. In FIG. 1, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a light emitting layer, 5 represents a hole blocking layer, 6 represents an electron transport layer, 7 represents an electron injection layer, and 8 represents a cathode.

[1] Substrate The substrate 1 serves as a support for the organic electroluminescent element, and quartz or glass plates, metal plates, metal foils, plastic films, sheets, and the like are used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

[2] Anode An anode 2 is provided on the substrate 1. The anode 2 plays a role of hole injection into a layer on the light emitting layer side (such as the hole injection layer 3 or the light emitting layer 4).

  This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or A conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline is used.

  In general, the anode 2 is often formed by sputtering, vacuum deposition, or the like. In addition, when forming an anode using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, or conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing and coating the substrate 1. Further, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).

  The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.

  The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

  The surface of the anode is treated with ultraviolet (UV) / ozone, oxygen plasma, or argon plasma for the purpose of removing impurities adhering to the anode and adjusting the ionization potential to improve hole injection. Is preferred.

[3] Hole injection layer Since the hole injection layer 3 is a layer for transporting holes from the anode 2 to the light emitting layer 4, the hole injection layer 3 preferably contains a hole transporting compound. More preferably, it contains a transporting compound and an electron accepting compound. Furthermore, the hole injection layer 3 may contain a binder resin that does not easily trap charges and a coating property improving agent as necessary.

  In particular, as the hole injection layer 3, a film is formed on the anode 2 by a wet film formation method using only an electron-accepting compound or an electron-accepting compound and a hole-transporting compound. It is preferable to form the composition for organic electroluminescent elements by a wet film-forming method.

(Hole transporting compound)
As the hole transporting compound, a compound having an ionization potential of 4.5 eV to 6.0 eV is preferable.
Examples of the hole transporting compound include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, in addition to the compounds exemplified as the hole transporting compound that may be contained in the composition for organic electroluminescent elements of the present invention. , Oligothiophene derivatives, polythiophene derivatives and the like. Of these, aromatic amine compounds are preferred from the viewpoints of amorphousness and visible light transmittance.
Of the aromatic amine compounds, aromatic tertiary amine compounds are particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

  The type of the aromatic tertiary amine compound is not particularly limited, but a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerization organic compound in which repeating units are linked) is more preferable from the viewpoint of the surface smoothing effect. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following general formula (VII).

（一般式（VII）中、Ａｒ^２１，Ａｒ^２２は各々独立して、置換基を有していてもよい芳香族炭化水素基、または置換基を有していてもよい芳香族複素環基を表す。Ａｒ^２３〜Ａｒ^２５は、各々独立して、置換基を有していてもよい２価の芳香族炭化水素基、または置換基を有していてもよい２価の芳香族複素環基を表す。Ｙは、下記の連結基群の中から選ばれる連結基を表す。また、Ａｒ^２１〜Ａｒ^２５のうち、同一のＮ原子に結合する二つの基は互いに結合して環を形成してもよい。）

（上記各式中、Ａｒ^３１〜Ａｒ^４１は、各々独立して、置換基を有していてもよい芳香族炭化水素環、または置換基を有していてもよい芳香族複素環由来の１価または２価の基を表す。Ｒ^１０１およびＲ^１０２は、各々独立して、水素原子または任意の置換基を表す。））

(In the general formula (VII), Ar ²¹ and Ar ²² each independently represents an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar ^{23 to} Ar ²⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. Y represents a linking group selected from the following group of linking groups, and among Ar ^{21 to} Ar ²⁵ , two groups bonded to the same N atom are bonded to each other to form a ring. May be.)

(In the above formulas, Ar ^{31 to} Ar ⁴¹ are each independently 1 derived from an aromatic hydrocarbon ring which may have a substituent, or an aromatic heterocyclic ring which may have a substituent. And R ¹⁰¹ and R ¹⁰² each independently represents a hydrogen atom or an optional substituent.)

As Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ , any monovalent or divalent group derived from any aromatic hydrocarbon ring or aromatic heterocyclic ring is applicable. These may be the same or different from each other. Moreover, you may have arbitrary substituents.

  Examples of the aromatic hydrocarbon ring include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring and the like.

  The aromatic heterocycle includes a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring , Synoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring and the like.

Moreover, as Ar < ²³ > -Ar < ²⁵ >, Ar < ³¹ > -Ar < ³⁵ >, Ar < ³⁷ > -Ar < ⁴⁰ >, the bivalent origin derived from the 1 type or 2 types or more of aromatic hydrocarbon ring and / or aromatic heterocycle which were illustrated above is shown. Two or more groups may be linked and used.

The group derived from the aromatic hydrocarbon ring and / or aromatic heterocycle of Ar ^{21 to} Ar ²⁵ and Ar ^{31 to} Ar ⁴¹ may further have a substituent.
The molecular weight of these substituents is usually 400 or less, preferably about 250 or less. The type of the substituent is not particularly limited, and examples thereof include one or more selected from the following substituent group D.

[Substituent group D]
An alkyl group having usually 1 or more, usually 10 or less, preferably 8 or less, such as a methyl group or an ethyl group; an alkenyl group having 2 or more, usually 11 or less, preferably 5 or less carbon atoms, such as a vinyl group. An alkynyl group having usually 2 or more, usually 11 or less, preferably 5 or less, such as an ethynyl group; an alkoxy having a carbon number of usually 1 or more, usually 10 or less, preferably 6 or less, such as a methoxy group or an ethoxy group; A group; an aryloxy group such as a phenoxy group, a naphthoxy group, a pyridyloxy group, etc., usually 4 or more, preferably 5 or more, usually 25 or less, preferably 14 or less; a carbon such as a methoxycarbonyl group or an ethoxycarbonyl group An alkoxycarbonyl group having a number of usually 2 or more, usually 11 or less, preferably 7 or less; a dimethylamino group, a diethylamino group or the like, and usually having 2 or more carbon atoms Usually 20 or less, preferably 12 or less dialkylamino group; diphenylamino group, ditolylamino group, N-carbazolyl group, etc., and usually diarylamino having 10 or more carbon atoms, preferably 12 or more, usually 30 or less, preferably 22 or less Group: an arylalkylamino group having 6 or more carbon atoms, preferably 7 or more, usually 25 or less, preferably 17 or less, such as a phenylmethylamino group; an acetyl group, a benzoyl group or the like, and usually having 2 or more carbon atoms, Usually an acyl group of 10 or less, preferably 7 or less; a halogen atom such as a fluorine atom or a chlorine atom; a haloalkyl group having a carbon number of usually 1 or more, usually 8 or less, preferably 4 or less, such as a trifluoromethyl group; An alkylthio group having 1 to 10 carbon atoms, preferably 6 or less, preferably 6 or less; An arylthio group having usually 4 or more, preferably 5 or more, usually 25 or less, preferably 14 or less, such as a ruthio group, a naphthylthio group, or a pyridylthio group; Or more, preferably 3 or more, usually 33 or less, preferably 26 or less silyl group; trimethylsiloxy group, triphenylsiloxy group, etc., the carbon number is usually 2 or more, preferably 3 or more, usually 33 or less, preferably 26 or less. A siloxy group; a cyano group; an aromatic hydrocarbon ring group having usually 6 or more, usually 30 or less, preferably 18 or less, such as a phenyl group or a naphthyl group; a carbon number such as a thienyl group or a pyridyl group. An aromatic heterocyclic group of 3 or more, preferably 4 or more, usually 28 or less, preferably 17 or less.

Ar ²¹ and Ar ²² are preferably monovalent groups derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, or a pyridine ring from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound. More preferred are a phenyl group and a naphthyl group.

Ar ^{23 to} Ar ²⁵ are preferably divalent groups derived from a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring from the viewpoint of heat resistance and hole injection / transport properties including redox potential. More preferably a group, a biphenylene group, or a naphthylene group.

As R ¹⁰¹ and R ¹⁰² , a hydrogen atom or an arbitrary substituent is applicable. These may be the same or different from each other. The type of the substituent is not particularly limited, and examples of applicable substituents include alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic rings. Group and halogen atom. Specific examples thereof include the groups exemplified in the above substituent group D.

  Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the general formula (VII) include those described in WO2005 / 089024, and preferred examples thereof are also the same. Although the compound (P1) represented by Structural Formula is mentioned, it is not limited to them at all.

  Preferable examples of the other aromatic tertiary amine polymer compounds include polymer compounds containing a repeating unit represented by the following general formula (VIII) and / or general formula (IX).

（一般式（VIII）、（IX）中、Ａｒ^４５，Ａｒ^４７およびＡｒ^４８は各々独立して、置換基を有していてもよい芳香族炭化水素基、または置換基を有していてもよい芳香族複素環基を表す。Ａｒ^４４およびＡｒ^４６は各々独立して、置換基を有していてもよい２価の芳香族炭化水素基、または置換基を有していてもよい２価の芳香族複素環基を表す。また、Ａｒ^４５〜Ａｒ^４８のうち、同一のＮ原子に結合する２つの基は互いに結合して環を形成してもよい。Ｒ^１１１〜Ｒ^１１３は各々独立して、水素原子または任意の置換基を表す。）

(In the general formulas (VIII) and (IX), Ar ⁴⁵ , Ar ⁴⁷ and Ar ⁴⁸ may each independently have an aromatic hydrocarbon group which may have a substituent, or a substituent. And each of Ar ⁴⁴ and Ar ⁴⁶ independently represents a divalent aromatic hydrocarbon group which may have a substituent, or a divalent which may have a substituent. In addition, two groups bonded to the same N atom among Ar ^{45 to} Ar ⁴⁸ may be bonded to each other to form a ring, and R ^{111 to} R ¹¹³ are each independently And represents a hydrogen atom or an arbitrary substituent.)

Specific examples of Ar ⁴⁵ , Ar ⁴⁷ , Ar ⁴⁸ and Ar ⁴⁴ , Ar ⁴⁶ , preferred examples, examples of substituents that may be included and examples of preferred substituents are Ar ²¹ , Ar ^22, and Ar ²³ ˜ Same as Ar ²⁵ . R ^{111 to} R ¹¹³ are preferably a hydrogen atom or a substituent described in [Substituent group D], more preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group, an aromatic hydrocarbon group, It is an aromatic hydrocarbon group.

  Specific examples of the aromatic tertiary amine polymer compound containing a repeating unit represented by the general formula (VIII) and / or (IX) include those described in WO2005 / 089024, and preferred examples thereof are also included. Although it is the same, it is not limited to them at all.

  Moreover, when forming a positive hole injection layer with a wet film-forming method, the positive hole transport compound which is easy to melt | dissolve in a various solvent is preferable. From the viewpoint of solvent solubility, as the aromatic tertiary amine compound, for example, a binaphthyl compound (Japanese Patent Laid-Open No. 2004-014187) and an asymmetric 1,4-phenylenediamine compound (Japanese Patent Laid-Open No. 2004-026732) are preferable.

  In addition, compounds that are easily dissolved in various solvents may be appropriately selected from aromatic amine compounds that have been conventionally used as a hole injection / transport thin film forming material in organic electroluminescence devices. Examples of the aromatic amine compound applicable to the hole-transporting compound of the hole-injecting layer include conventionally known compounds that have been utilized as a hole-injecting / transporting layer-forming material in organic electroluminescence devices. It is done. For example, an aromatic diamine compound in which a tertiary aromatic amine unit such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane is linked (JP 59-194393 A); 4,4′- An aromatic amine compound containing two or more tertiary amines represented by bis [N- (1-naphthyl) -N-phenylamino] biphenyl and having two or more condensed aromatic rings substituted with nitrogen atoms No. 5-23481); an aromatic triamine compound having a starburst structure as a derivative of triphenylbenzene (US Pat. No. 4,923,774); N, N′-diphenyl-N, N′-bis (3- Aromatic diamine compounds such as methylphenyl) biphenyl-4,4′-diamine (US Pat. No. 4,764,625); α, α, α ′, α′-tetramethyl-α, α′- (4-di (p-tolyl) aminophenyl) -p-xylene (Japanese Patent Laid-Open No. 3-269084); sterically asymmetric triphenylamine derivative as a whole molecule (Japanese Patent Laid-Open No. 4-129271); pyrenyl A compound in which a plurality of aromatic diamino groups are substituted on the group (Japanese Patent Laid-Open No. 4-175395); an aromatic diamine compound in which a tertiary aromatic amine unit is linked with an ethylene group (Japanese Patent Laid-Open No. 4-264189); a styryl structure An aromatic diamine having a thiophene group (JP-A-4-290851); a compound in which an aromatic tertiary amine unit is linked by a thiophene group (JP-A-4-304466); a starburst type aromatic triamine compound (JP-A-4-30481) 308688); benzylphenyl compound (Japanese Patent Laid-Open No. 4-364153); Compounds in which thiones are linked (JP-A-5-25473); triamine compounds (JP-A-5-239455); bisdipyridylaminobiphenyl (JP-A-5-320634); N, N, N-triphenylamine Derivatives (JP-A-6-1972); Aromatic diamines having a phenoxazine structure (JP-A-7-138562); Diaminophenylphenanthridine derivatives (JP-A-7-252474); 2-311591); silazane compounds (US Pat. No. 4,950,950); silanamine derivatives (JP-A-6-49079); phosphamine derivatives (JP-A-6-25659); quinacridone compounds, etc. Can be mentioned. These aromatic amine compounds may be used in combination of two or more as required.

  Preferred specific examples of the phthalocyanine derivative or porphyrin derivative applicable to the hole transporting compound of the hole injection layer include porphyrin, 5,10,15,20-tetraphenyl-21H, 23H-porphyrin, 5,10 , 15,20-tetraphenyl-21H, 23H-porphyrin cobalt (II), 5,10,15,20-tetraphenyl-21H, 23H-porphyrin copper (II), 5,10,15,20-tetraphenyl- 21H, 23H-porphyrin zinc (II), 5,10,15,20-tetraphenyl-21H, 23H-porphyrin vanadium (IV) oxide, 5,10,15,20-tetra (4-pyridyl) -21H, 23H -Porphyrin, 29H, 31H-phthalocyanine copper (II), phthalocyanine zinc (II), Russia Nin titanium, phthalocyanine oxide magnesium, phthalocyanine lead, phthalocyanine copper (II), 4,4 ', 4 ", 4' '' - tetraaza-29H, 31H-phthalocyanine, and the like.

  Further, preferred specific examples of the oligothiophene derivative applicable as the hole transporting compound of the hole injection layer include α-terthiophene and its derivatives, α-sexithiophene and its derivatives, and oligothiophene containing a naphthalene ring. Derivatives (JP-A-6-256341) and the like.

  Further, preferred specific examples of the polythiophene derivative applicable as the hole transporting compound in the present invention include poly (3,4-ethylenedioxythiophene) (PEDOT), poly (3-hexylthiophene) and the like.

  The molecular weight of these hole transporting compounds is usually 9000 or less, preferably 5000 or less, and usually 200 or more, preferably 400 or more, except in the case of a polymer compound (a polymerizable compound in which repeating units are continuous). Range. If the molecular weight of the hole transporting compound is too high, synthesis and purification are difficult, which is not preferable. On the other hand, if the molecular weight is too low, the heat resistance may be lowered, which is also not preferable.

  The hole transporting compound used as the material for the hole injection layer may contain any one of these compounds alone, or may contain two or more. When two or more hole transporting compounds are contained, the combination thereof is arbitrary, but one or more of aromatic tertiary amine polymer compounds and one of other hole transporting compounds or Two or more types are preferably used in combination.

(Electron-accepting compound)
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is further more preferable.

  Examples of such electron-accepting compounds include onium salts substituted with organic groups such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, iron (III) chloride (Japanese Patent Laid-Open No. 11-251067). ), High valent inorganic compounds such as ammonium peroxodisulfate, cyano compounds such as tetracyanoethylene, aromatic boron compounds such as tris (pentafluorophenyl) borane (JP-A-2003-31365), fullerene derivatives, iodine, and the like. It is done.

  Of the above-mentioned compounds, onium salts substituted with organic groups and high-valent inorganic compounds are preferable in terms of having strong oxidizing power, and organic groups are preferable in that they are soluble in various solvents and applicable to wet film formation. Substituted onium salts, cyano compounds, and aromatic boron compounds are preferred.

  Specific examples of an onium salt substituted with an organic group, a cyano compound, and an aromatic boron compound suitable as an electron-accepting compound include those described in WO 2005/089024, and suitable examples thereof are also the same. Although the compound (A1) represented by following structural formula is mentioned, it is not limited to them at all.

  The hole injection layer 3 is formed on the anode 2 by a wet film formation method or a vacuum deposition method.

  ITO (indium tin oxide), which is generally used as the anode 2, has a surface roughness of about 10 nm (Ra) and, in addition, often has protrusions locally, resulting in short-circuit defects. There was a problem that it was easy to produce. When the hole injection layer 3 formed on the anode 2 is formed by the wet film forming method, the defect of the element is generated due to the unevenness of the surface of the anode as compared with the case of forming by the vacuum deposition method. Has the advantage of reducing.

  In the case of layer formation by a wet film-forming method, a predetermined amount of one or more of the above-mentioned materials is added to a binder resin or coating property improving agent that does not become a charge trap if necessary, and dissolved in a solvent. The coating solution is prepared, applied onto the anode by a wet film formation method such as spin coating, spray coating, dip coating, die coating, flexographic printing, screen printing, and ink jet method, and dried to form the hole injection layer 3. Let it form.

  The solvent used for the layer formation by the wet film forming method is not particularly limited as long as it is a solvent capable of dissolving the above-described materials, and is used for the composition for an organic electroluminescent element. It may be a solvent.

  Examples of other solvents include aromatic solvents, aliphatic solvents, and amide solvents. Specifically, as the aromatic solvent, 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethyl Aromatic ethers such as anisole and 2,4-dimethylanisole; aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate; and others, benzene, toluene, Examples include xylene and 2-phenoxyethyl acetate. Examples of aliphatic solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA); ethyl acetate, n-butyl acetate, ethyl lactate, n-butyl lactate, etc. Aliphatic esters of dimethyl sulfoxide and the like. Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide and the like. Any one of these may be used alone, or two or more thereof may be used in any combination and ratio.

  Examples thereof include aromatic hydrocarbon solvents such as benzene, toluene and xylene, amide solvents such as N, N-dimethylformamide and N, N-dimethylacetamide, and dimethyl sulfoxide. Any one of these may be used alone, or two or more thereof may be used in any combination and ratio.

  The concentration of the solvent in the coating solution is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99.999% by weight or less, preferably 99.99% by weight or less. Preferably it is the range of 99.9 weight% or less. When two or more kinds of solvents are mixed and used, the total of these solvents is set to satisfy this range.

In the case of forming a layer by vacuum deposition, one or more of the above-mentioned materials are placed in a crucible installed in a vacuum vessel (in the case of using two or more materials, put in each crucible), and vacuum is applied. After evacuating the inside of the container to about 10 ⁻⁴ Pa with a suitable vacuum pump, the crucible is heated (if each kind of material is used, each crucible is heated), and the evaporation amount is controlled to evaporate ( When two or more kinds of materials are used, the evaporation amount is independently controlled to evaporate), and the hole injection layer 3 is formed on the anode 2 of the substrate placed facing the crucible. In addition, when using 2 or more types of materials, they can also be put into a crucible, can be heated and evaporated, and can be used for positive hole injection layer formation.

The film thickness of the hole injection layer 3 that may be formed in this manner is usually in the range of 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.
The hole injection layer 3 may be omitted.

[4] Light-Emitting Layer A normal light-emitting layer 4 is provided on the hole injection layer 3. The light emitting layer 4 is a layer containing a light emitting material, and between the electrodes to which an electric field is applied, holes injected from the anode 2 through the hole injection layer 3 and electrons injected from the cathode 6 through the electron transport layer 5 It is a layer that is excited by recombination and becomes a main light emitting source. The light-emitting layer 4 preferably contains a light-emitting material (dopant) and one or more host materials, and may be formed by a vacuum deposition method, but the composition for organic electroluminescent elements of the present invention is used. A layer produced by a wet film formation method is particularly preferred.

  As the material contained in the light emitting layer, the light emitting material, the hole transporting material, and the electron transporting material described as the materials included when the composition for organic electroluminescence device of the present invention is used for forming the light emitting layer. Is mentioned. In addition, the light emitting layer 4 may contain other materials and components as long as the performance of the present invention is not impaired.

  In general, when the same material is used in the organic electroluminescent element, the thinner the film thickness between the electrodes, the larger the effective electric field, so that the injected current increases, so the driving voltage decreases. For this reason, the driving voltage of the organic electroluminescence device decreases when the total film thickness between the electrodes is thin, but if it is too thin, a short circuit occurs due to the protrusion caused by the electrode such as ITO. Necessary.

In the present invention, in addition to the light emitting layer 4, when the organic layer such as the hole injection layer 3 and the electron transport layer 5 described later is provided, the light emitting layer 4 and other organic materials such as the hole injection layer 3 and the electron transport layer 5 are used. The total film thickness combined with the layer is usually 30 nm or more, preferably 50 nm or more, more preferably 100 nm or more, usually 1000 nm or less, preferably 500 nm or less, more preferably 300 nm or less.
In addition, when the conductivity of the hole injection layer 3 other than the light emitting layer 4 and the electron injection layer 5 described later is high, the amount of charge injected into the light emitting layer 4 increases. It is also possible to reduce the drive voltage while increasing the thickness to reduce the thickness of the light emitting layer 4 and maintaining the total thickness to some extent.

  Therefore, the thickness of the light emitting layer 4 is usually 10 nm or more, preferably 20 nm or more, and usually 300 nm or less, preferably 200 nm or less. When the element of the present invention has only the light emitting layer 4 between the anode 2 and the cathode 6, the thickness of the light emitting layer 4 is usually 30 nm or more, preferably 50 nm or more, usually 500 nm or less, preferably 300 nm. It is as follows.

[5] Hole blocking layer The hole blocking layer 5 has a function of confining holes and electrons in the light emitting layer 4 and improving the light emission efficiency. That is, the hole blocking layer 5 is generated by increasing the probability of recombination with electrons in the light emitting layer 4 by blocking the holes moving from the light emitting layer 4 from reaching the electron transport layer 6. There is a role of confining excitons in the light emitting layer 4 and a role of efficiently transporting electrons injected from the electron transport layer 6 in the direction of the light emitting layer 4. In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting substance, it is effective to provide the hole blocking layer 5.

  The hole blocking layer 5 prevents the holes moving from the anode 2 from reaching the cathode 8 and can efficiently transport the electrons injected from the cathode 8 toward the light emitting layer 4. The compound is laminated on the light emitting layer 4 so as to be in contact with the interface on the cathode 8 side of the light emitting layer 4.

  The physical properties required of the material constituting the hole blocking layer 5 include high electron mobility, low hole mobility, large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high.

  Examples of the hole blocking layer material satisfying such conditions include mixed arrangements of bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum, and the like. Ligand complexes, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, styryl compounds such as distyrylbiphenyl derivatives ( JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole (JP-A-7-41759) And phenanthroline derivatives such as bathocuproine (Japanese Patent Laid-Open No. 10-79297).

  Furthermore, a compound having at least one pyridine ring substituted at the 2,4,6-positions described in WO2005 / 022962 is also preferable as the hole blocking material.

  The film thickness of the hole blocking layer 5 is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

  The hole blocking layer 5 can also be formed by the same method as the hole injection layer 3, but a vacuum deposition method is usually used.

  The electron transport layer 6 and the hole blocking layer 5 described later may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole block layer, and 3) The hole block layer / electron transport layer There are usages such as stacking, 4) not using, etc.

[6] Electron Transport Layer The electron transport layer 6 is provided between the light emitting layer 4 and the electron injection layer 7 for the purpose of further improving the light emission efficiency of the device.

  The electron transport layer 6 is formed of a compound that can efficiently transport electrons injected from the cathode 8 between the electrodes to which an electric field is applied in the direction of the light emitting layer 4. As the electron transporting compound used for the electron transport layer 6, the electron injection efficiency from the cathode 8 or the electron injection layer 7 is high, and the injected electrons having high electron mobility can be efficiently transported. It must be a compound.

  Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives, Styryl biphenyl derivative, silole derivative, 3- or 5-hydroxyflavone metal complex, benzoxazole metal complex, benzothiazole metal complex, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compound No. 207169), phenanthroline derivatives (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide, n-type sulfide Examples include zinc and n-type zinc selenide.

  The lower limit of the thickness of the electron transport layer 6 is usually 1 nm, preferably about 5 nm, and the upper limit is usually about 300 nm, preferably about 100 nm.

  The electron transport layer 6 is formed by laminating on the light emitting layer 4 by a wet film formation method or a vacuum deposition method in the same manner as the hole injection layer 3. Usually, a vacuum deposition method is used.

[7] Electron Injection Layer The electron injection layer 7 serves to efficiently inject electrons injected from the cathode 8 into the light emitting layer 4. In order to perform electron injection efficiently, the material for forming the electron injection layer 7 is preferably a metal having a low work function, and alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium are used.

  The film thickness of the electron injection layer 7 is preferably 0.1 to 5 nm.

Further, it is possible to insert an ultrathin insulating film (0.1 to 5 nm) such as LiF, MgF ₂ , Li ₂ O, Cs ₂ CO _{3 at} the interface between the cathode 8 and the light emitting layer 4 or the electron transport layer 6. (Appl. Phys. Lett., 70, 152, 1997; JP-A-10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997; SID 04 Digest, page 154).

  Furthermore, organic metal transport materials represented by metal complexes such as nitrogen-containing heterocyclic compounds such as bathophenanthroline and aluminum complexes of 8-hydroxyquinoline described later are doped with alkali metals such as sodium, potassium, cesium, lithium and rubidium. (Described in JP-A-10-270171, JP-A 2002-1000047, JP-A 2002-1000048, and the like) makes it possible to improve electron injection / transport properties and achieve excellent film quality. Therefore, it is preferable. The film thickness in this case is usually 5 nm or more, preferably 10 nm or more, and usually 200 nm or less, preferably 100 nm or less.

The electron injection layer 7 is formed by laminating on the light emitting layer 4 by a wet film forming method or a vacuum vapor deposition method in the same manner as the light emitting layer 4. In the case of the vacuum evaporation method, the evaporation source is put into a crucible or metal boat installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with an appropriate vacuum pump, and then the crucible or metal boat is Heat and evaporate to form an electron injection layer on the substrate placed facing the crucible or metal boat.

The alkali metal is deposited using an alkali metal dispenser in which nichrome is filled with an alkali metal chromate and a reducing agent. By heating the dispenser in a vacuum container, the alkali metal chromate is reduced and the alkali metal is evaporated. In the case of co-evaporating the organic electron transport material and the alkali metal, the organic electron transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ⁻⁴ Pa with a suitable vacuum pump. Each crucible and dispenser are heated simultaneously to evaporate to form an electron injection layer on the substrate placed facing the crucible and dispenser.

  At this time, co-evaporation is uniformly performed in the film thickness direction of the electron injection layer 7, but there may be a concentration distribution in the film thickness direction.

  The electron injection layer 7 may be omitted.

[8] Cathode The cathode 8 plays a role of injecting electrons into a layer on the light emitting layer side (such as the electron injection layer 7 or the light emitting layer 4). The material used for the cathode 8 can be the material used for the anode 2, but a metal having a low work function is preferable for efficient electron injection, and tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

  The film thickness of the cathode 8 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.

[9] Other Constituent Layers Although the above description has focused on the element having the layer structure shown in FIG. 1, the performance between the anode 2 and cathode 8 and the light emitting layer 4 in the organic electroluminescent element of the present invention is not limited. In addition to the layers described above, any layer may be included, and any layer other than the light emitting layer 4 may be omitted.

  For example, it is also effective to provide an electron blocking layer between the hole injection layer 3 and the light emitting layer 4 for the same purpose as the hole blocking layer 5. The electron blocking layer increases the probability of recombination with holes in the light emitting layer 4 by blocking electrons moving from the light emitting layer 4 from reaching the hole injection layer 3, There is a role of confining in the light emitting layer 4 and a role of efficiently transporting holes injected from the hole injection layer 3 in the direction of the light emitting layer 4.

  The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Further, when the light emitting layer 4 is formed by a wet film forming method, it is preferable to form the electron blocking layer by a wet film forming method because the device manufacturing becomes easy.

  For this reason, it is preferable that the electron blocking layer also has wet film formation compatibility. As a material used for such an electron blocking layer, in addition to the charge transport material of the present invention, dioctylfluorene represented by F8-TFB and And a copolymer of triphenylamine (described in WO 2004/084260).

  Moreover, it is preferable in this invention to have a positive hole transport layer. Moreover, the compound illustrated as a hole transportable compound of the said positive hole injection layer can also be used. Alternatively, a polymer material such as polyarylene ether sulfone containing polyvinyl carbazole, polyvinyl triphenylamine, or tetraphenylbenzidine may be used. The hole transport layer is formed by laminating these materials on the hole injection layer by a wet film formation method or a vacuum deposition method. The film thickness of the hole transport layer thus formed is usually 10 nm or more, preferably 30 nm. However, it is usually 300 nm or less, preferably 100 nm or less.

  The structure opposite to that shown in FIG. 1, that is, a cathode 8, an electron injection layer 7, an electron transport layer 6, a hole blocking layer 5, a light emitting layer 4, a hole injection layer 3, and an anode 2 are laminated on the substrate 1 in this order. As described above, the organic electroluminescent element of the present invention can be provided between two substrates, at least one of which is highly transparent.

Further, a structure in which a plurality of layers shown in FIG. 1 are stacked (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interfacial layer (between the light emitting units) (when the anode is ITO and the cathode is Al, the two layers), for example, V ₂ O ₅ is used as the charge generation layer (CGL). This is more preferable from the viewpoint of luminous efficiency and driving voltage.

  The present invention can be applied to any of an organic electroluminescent element having a single element, an element having a structure arranged in an array, and a structure having an anode and a cathode arranged in an XY matrix.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited to description of a following example, unless the summary is exceeded.

Example 1
The organic electroluminescent element shown in FIG. 1 was produced.
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Sanyo Vacuum Co., Ltd., sputtered film product) using ordinary photolithography technology and hydrochloric acid etching Then, the anode 2 was formed by patterning into stripes having a width of 2 mm. The patterned ITO substrate is cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water cleaning with ultrapure water, ultrasonic cleaning with ultrapure water, and water cleaning with ultrapure water, followed by drying with compressed air, and finally UV irradiation. Ozone cleaning was performed.

  First, 2% by weight of a hole transporting polymer material having a repeating structure represented by the following structural formula (P1) and 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluoro) represented by the following structural formula (A1) After dissolving 0.8% by weight of phenyl) borate in ethyl benzoate as a solvent, it was filtered using a PTFE (polytetrafluoroethylene) membrane filter having a pore size of 0.2 μm to prepare a coating composition. This coating composition was spin-coated on the glass substrate. The spin coating was performed in an air atmosphere at a temperature of 23 ° C. and a relative humidity of 60%, the spinner rotation speed was 1500 rpm, and the spinner time was 30 seconds. After spin coating, it was heated and dried on a hot plate at 80 ° C. for 1 minute, and then heated in an oven at 230 ° C. for 180 minutes in an atmospheric atmosphere. In this way, a hole injection layer 3 having a thickness of 30 nm was formed.

  Next, 1.5% by weight of a compound represented by the following structural formula (C1), 1.5% by weight of a compound represented by the following structural formula (C2), and a compound represented by the following structural formula (C3) The organic electric field of the present invention was prepared by dissolving 0.15% by weight in Fencon (boiling point 192 ° C.), which is an alicyclic ketone compound, and filtering using a PTFE (polytetrafluoroethylene) membrane filter having a pore size of 0.2 μm. A composition for a light emitting device was prepared. This composition for organic electroluminescent elements was applied onto the previous hole injection layer by spin coating to form a light emitting layer 4. Spin coating was performed in a nitrogen atmosphere glove box, the spinner rotation speed was 1500 rpm, and the spinner time was 30 seconds. After the application, it was dried by heating at a vacuum of 0.01 MPa and 130 ° C. for 1 hour.

Next, the substrate on which the hole injection layer 3 and the light emitting layer 5 are formed by the wet film forming method is carried into a vacuum vapor deposition apparatus, and after the apparatus is roughly evacuated by an oil rotary pump, the degree of vacuum in the apparatus is increased. It is evacuated using a cryopump until the pressure becomes 5.0 × 10 ⁻⁶ Torr (6.7 × 10 ⁻⁴ Pa) or less, and a compound represented by the following structural formula (C4) is stacked by a vacuum deposition method. A hole blocking layer 5 was obtained. At this time, the degree of vacuum at the time of vapor deposition is 1.2 to 2.0 × 10 ⁻⁶ Torr (2.7 × 10 ⁻⁴ Pa), and the vapor deposition rate is controlled within a range of 0.8 to 0.9 kg / sec. A hole blocking layer 5 was formed by laminating a film having a thickness of 5 nm on the light emitting layer 4.

Subsequently, vapor deposition was performed by heating tris (8-hydroxyquinolinate) aluminum to form an electron transport layer 6. The degree of vacuum during vapor deposition is controlled in the range of 1.0 to 1.5 × 10 ⁻⁶ Torr (1.3 to 2.0 × 10 ⁻⁴ Pa), and the vapor deposition rate is controlled in the range of 0.8 to 1.3 liters / second. The electron transport layer 6 was formed by laminating a film having a thickness of 30 nm on the hole blocking layer 5.

Here, the element that has been vapor-deposited up to the electron transport layer 6 is once taken out from the vacuum vapor deposition apparatus into the atmosphere, and a 2 mm wide stripe-shaped shadow mask is used as the cathode vapor deposition mask. The device was placed in close contact with each other so as to be orthogonal to each other, placed in another vacuum vapor deposition apparatus, and evacuated until the degree of vacuum in the apparatus became 1.0 × 10 ⁻⁴ Pa or less in the same manner as in the organic layer vapor deposition.

As the electron injection layer 7, first, lithium fluoride (LiF) was controlled at a deposition rate of 0.1 to 0.15 liters / second and a degree of vacuum of 2.3 to 6.7 × 10 ⁻⁵ Pa using a molybdenum boat. The film was formed on the electron transport layer 6 with a film thickness of 0.5 nm. Next, aluminum as a cathode 8 is similarly heated by a molybdenum boat and controlled at a deposition rate of 0.9 to 5.0 liters / second and a degree of vacuum of 2.5 to 15 × 10 ⁻⁵ Pa. A layer was formed. The substrate temperature during the deposition of the electron injection layer 7 and the cathode 8 was kept at room temperature.

Subsequently, in order to prevent the element from being deteriorated by moisture in the atmosphere during storage, a sealing process was performed by the method described below.
In a nitrogen glove box connected to a vacuum vapor deposition device, a photocurable resin (30Y-437 manufactured by ThreeBond Co., Ltd.) with a width of about 1 mm is applied to the outer peripheral portion of a 23 mm × 23 mm size glass plate, and the central portion is applied. A moisture getter sheet (manufactured by Dynic Co., Ltd.) was installed. On this, the board | substrate which complete | finished cathode formation was bonded together so that the vapor-deposited surface might oppose a desiccant sheet. Then, only the area | region where the photocurable resin was apply | coated was irradiated with ultraviolet light, and resin was hardened.
As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained.

  Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.

In Table 1, the light emission luminance retention rate is a ratio of luminance after 50 seconds from the initial value when the luminance change with time was observed at a current density of 250 mA / cm ² when the initial luminance was 1. The driving lifetimes 1 to 3 are as follows.
Driving lifetime 1: room temperature, energization time when light emission luminance at the start of energization constant DC current is continuously energized at a constant current value to be 5000 cd / ^{m 2,} luminous brightness became 2500 cd / ^{m 2.}
Driving lifetime 2: room temperature, a constant DC current is continuously energized with a constant current emission luminance at the start of energization is 2500 cd / ^{m 2,} the energization time when the light emission luminance becomes 1250cd / ^{m 2.}
Driving life 3: Current-carrying time when the constant current of direct current is applied at a constant current value at which the light emission luminance is 1000 cd / m ² at room temperature and the light emission luminance is 500 cd / m ² at room temperature.

  As shown in Table 1, it is apparent that a high-luminance and high-efficiency device was obtained by using Fencon, which is an alicyclic ketone-based compound, as a solvent for the composition for forming a light emitting layer.

(Example 2)
In the same manner as in Example 1, except that 3,3,5-trimethylcyclohexanone (boiling point 189 ° C.) was used in place of Fencon as the alicyclic ketone-based compound of the organic electroluminescent element composition for forming the light emitting layer. The organic electroluminescent element shown in FIG. 1 was produced.

Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.
As shown in Table 1, it is clear that a high-luminance and high-efficiency device was obtained by using an alicyclic ketone-based compound as a solvent for the composition for forming a light emitting layer.

(Example 3)
In the composition for organic electroluminescence device for forming a light emitting layer, the compound represented by the structural formula (C1), the compound represented by the structural formula (C2), and the compound represented by the structural formula (C3) are contained. The amount is shown in FIG. 1 in the same manner as in Example 1 except that (C1) is changed to 0.8% by weight, (C2) is changed to 0.8% by weight, and (C3) is changed to 0.08% by weight. An organic electroluminescent element was produced.

Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.
As shown in Table 1, it is clear that a high-luminance and high-efficiency device was obtained by using an alicyclic ketone-based compound as a solvent for the composition for forming a light emitting layer.

(Comparative Example 1)
The organic electroluminescent element shown in FIG. 1 was produced in the same manner as in Example 1 except that isoamyl benzoate was used in place of Fencon in the composition for organic electroluminescent element for forming a light emitting layer.
Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.

(Comparative Example 2)
The organic electroluminescent element shown in FIG. 1 was produced in the same manner as in Example 1 except that cyclohexylbenzene was used in place of Fencon in the composition for organic electroluminescent element for forming a light emitting layer.
Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.

(Comparative Example 3)
In the composition for organic electroluminescence device for forming a light emitting layer, the compound represented by the structural formula (C1), the compound represented by the structural formula (C2), and the compound represented by the structural formula (C3) are contained. Except that the amount was changed to 1.25% by weight of (C1), 1.25% by weight of (C2), 0.125% by weight of (C3), and isoamyl benzoate was used in place of Fencon. The organic electroluminescent element shown in FIG.
Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.

(Comparative Example 4)
In the composition for organic electroluminescence device for forming a light emitting layer, the compound represented by the structural formula (C1), the compound represented by the structural formula (C2), and the compound represented by the structural formula (C3) are contained. Example 1 except that (C1) was changed to 1.3% by weight, (C2) was changed to 1.3% by weight, and (C3) was changed to 0.13% by weight, and cyclohexylbenzene was used instead of Fencon. In the same manner, the organic electroluminescent element shown in FIG. 1 was produced.
Table 1 shows the light emission characteristics and the driving life of the obtained organic electroluminescence device.

(Comparative Example 5)
In the composition for organic electroluminescence device for forming a light emitting layer, the compound represented by the structural formula (C1), the compound represented by the structural formula (C2), and the compound represented by the structural formula (C3) are contained. The amount was changed to 1.5% by weight of (C1), 1.5% by weight of (C2), and 0.15% by weight of (C3), and cyclohexanone (boiling point 155 ° C.) was used instead of Fencon. The organic electroluminescent element shown in FIG. 1 was produced in the same manner as Example 1 except for the above.
The emission characteristics of the obtained organic electroluminescent element are shown in Table 1.

(Comparative Example 6)
In the composition for organic electroluminescence device for forming a light emitting layer, the compound represented by the structural formula (C1), the compound represented by the structural formula (C2), and the compound represented by the structural formula (C3) are contained. The amount was changed to 1.0% by weight for (C1), 1.0% by weight for (C2), and 0.1% by weight for (C3), except that cyclohexanone was used instead of fencon. The organic electroluminescent element shown in FIG.
The emission characteristics of the obtained organic electroluminescent element are shown in Table 1.

Example 4
Example 4 was performed according to the following procedure.
The glass substrate was cleaned in the order of ultrasonic cleaning with a surfactant aqueous solution and then with ultrapure water, then dried with compressed air, and finally subjected to ultraviolet ozone cleaning.
First, 2% by weight of a hole transporting polymer material having a repeating structure represented by the structural formula (P1) and 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) represented by the structural formula (A1). After 0.4% by weight of borate was dissolved in ethyl benzoate as a solvent, it was filtered using a PTFE (polytetrafluoroethylene) membrane filter having a pore size of 0.2 μm to prepare a coating composition. This coating composition was spin-coated on the glass substrate. The spin coating was performed in an air atmosphere at a temperature of 23 ° C. and a relative humidity of 40%, the spinner rotation speed was 1500 rpm, and the spinner time was 30 seconds. After spin coating, it was heated and dried on a hot plate at 80 ° C. for 1 minute, and then heated in an oven at 230 ° C. for 3 hours in an atmospheric atmosphere. In this way, a hole injection layer having a thickness of 30 nm was formed.

Next, a part of the thin film of the hole injection layer formed on the glass substrate is scraped, a step is formed between the glass substrate and the thin film, and a stylus type film thickness meter (manufactured by KLA-Tencor Corporation) is used. the initial film thickness _{H 1} were measured.
Next, a glass substrate with a hole injection layer whose initial film thickness was determined was placed on a spin coater, and Fencon was dropped on the hole injection layer to form a droplet. After holding the droplet for 10 minutes, the spinner Spin-out was performed at a rotation speed of 1500 rpm and a spinner time of 30 seconds to remove the droplets.
Thereafter, the substrate from which the droplets have been removed is dried for 12 minutes at a temperature of 230 ° C., and the film thickness H ₂ after the test is again measured with a stylus-type film thickness meter, and the remaining film thickness ratio H ₂ / H ₁ × 100 (%) was calculated.
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to the fencon. As shown in Table 2, the alicyclic ketone solvent has a high residual film thickness ratio.

(Example 5)
The remaining film thickness ratio was calculated in the same manner as in Example 4 except that Fencon was changed to 3,3,5-trimethylcyclohexanone.
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to 3,3,5-trimethylcyclohexanone. As shown in Table 2, the alicyclic ketone solvent has a high residual film thickness ratio.

(Example 6)
The residual film thickness ratio was calculated in the same manner as in Example 4 except that the fencon was changed to 2-n-hexylcyclopentanone (boiling point 246 ° C.).
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to 2-n-hexylcyclopentanone. As shown in Table 2, the alicyclic ketone solvent has a high residual film thickness ratio.

(Example 7)
The remaining film thickness ratio was calculated in the same manner as in Example 4 except that Fencon was changed to Mentone (boiling point 209 ° C.).
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to menthone. As shown in Table 2, the alicyclic ketone solvent has a high residual film thickness ratio.

(Comparative Example 7)
The remaining film thickness ratio was calculated in the same manner as in Example 4 except that fenkon was changed to benzyl methyl ether.
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to benzyl methyl ether. As shown in Table 2, the residual film thickness ratio is lower than that of the alicyclic ketone solvent.

(Comparative Example 8)
The remaining film thickness ratio was calculated in the same manner as in Example 4 except that fencon was changed to 1′-acetonaphthone.
Table 2 shows the remaining film thickness ratio with respect to 1′-acetonaphthone of the obtained hole injection layer. As shown in Table 2, the residual film thickness ratio is lower than that of the alicyclic ketone solvent.

(Comparative Example 9)
The remaining film thickness ratio was calculated in the same manner as in Example 4 except that Fencon was changed to dibenzyl ether.
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to dibenzyl ether. As shown in Table 2, the residual film thickness ratio is lower than that of the alicyclic ketone solvent.

(Comparative Example 10)
The remaining film thickness ratio was calculated in the same manner as in Example 4 except that Fencon was changed to cyclohexyl acetate.
Table 2 shows the remaining film thickness ratio of the obtained hole injection layer with respect to cyclohexyl acetate. As shown in Table 2, the residual film thickness ratio is lower than that of the alicyclic ketone solvent.

It is typical sectional drawing which showed an example of the organic electroluminescent element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Light emitting layer 5 Hole blocking layer 6 Electron transport layer 7 Electron injection layer 8 Cathode

Claims (6)

  A composition used for forming an organic layer of an organic electroluminescent device, comprising an alicyclic ketone-based compound having a boiling point of 160 ° C. or higher as a solvent component thereof. object.   Furthermore, the composition for organic electroluminescent elements of Claim 1 containing a luminescent material.   A method for producing an organic electroluminescent device comprising an anode, a cathode, and an organic layer disposed between the anode and the cathode on a substrate, wherein at least one of the organic layers is defined in claim 1 or 2. It forms using the composition for organic electroluminescent elements of description, The manufacturing method of the organic electroluminescent element characterized by the above-mentioned.   The organic layer has a first organic layer and a second organic layer adjacent to each other, and the first organic layer is formed on the first organic layer after forming the first organic layer by a wet film forming method. The method for producing an organic electroluminescent element according to claim 3, wherein the second organic layer is formed by a wet film forming method using the composition for an organic electroluminescent element according to claim 4.   The method of manufacturing an organic electroluminescent element according to claim 4, wherein the first organic layer is a hole injection layer.   An organic electroluminescence device manufactured by the manufacturing method according to claim 3.

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